如何在不退出 python 脚本的情况下销毁一个 QApplication 然后运行一个新的？

Question

我想创建一个 QApplication，然后使用键盘快捷键退出。然后python脚本应该调用另一个QApplication。

我目前的问题是当第二个 QApplication 即将运行时出现此错误：

app2 = QApplication()
RuntimeError: Please destroy the QApplication singleton before creating a new QApplication instance.

我有以下结构：

| main.py
| Q1.py
| Q2.py

这是 main.py：

import Q1 as record
import Q2 as display

def main():
    record.main()
    display.main()


if __name__ == "__main__":
    main()

这是造成问题的第一季度：

import sys
from PySide2 import QtWidgets as qtw
from PySide2 import QtGui as qtg
from PySide2 import QtCore as qtc
from PySide2 import QtMultimedia as qtmm


class MainWindow(qtw.QMainWindow):
    def __init__(self):
        super().__init__()

        #Create Window layout with a sound widget
        soundboard = qtw.QWidget()
        soundboard.setLayout(qtw.QGridLayout())
        self.setCentralWidget(soundboard)
        sw = SoundWidget()
        soundboard.layout().addWidget(sw)

        #Window Dimensions
        self.setSizePolicy(qtw.QSizePolicy.Expanding, qtw.QSizePolicy.MinimumExpanding)

        # Code ends here
        self.show()


class SendOrderButton(qtw.QPushButton):
    button_stylesheet = 'background-color: blue; color: white;'

    def __init__(self):
        super().__init__('Send Order')
        self.setSizePolicy(qtw.QSizePolicy.Expanding, qtw.QSizePolicy.Expanding)
        self.setStyleSheet(self.button_stylesheet)
        #self.clicked.connect(qtc.QCoreApplication.instance().quit)

    def press_button(self):
        if self.isEnabled():
            self.setEnabled(False)
            self.setText('Send Order')
        else:
            self.setEnabled(True)
            self.setText('Sent')

class SoundWidget(qtw.QWidget):
    def __init__(self):
        super().__init__()
        self.setLayout(qtw.QGridLayout())

        #Send Order Button
        self.sendorder_button = SendOrderButton()
        self.sendorder_button.setShortcut(qtg.QKeySequence('Tab'))
        self.layout().addWidget(self.sendorder_button, 5, 0, 1, 2)
        self.sendorder_button.clicked.connect(qtc.QCoreApplication.instance().quit)

def main():
    app = qtw.QApplication(sys.argv)
    window = MainWindow()
    window.show()
    app.exec_()

if __name__ == '__main__':
    app = qtw.QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())

这是具有第二个 QApplication 的 Q2.py：

import sys
from PySide2.QtCore import (QAbstractTableModel, Slot)
from PySide2.QtWidgets import (QAction, QApplication, QMainWindow,QWidget)

class MainWindow(QMainWindow):
    def __init__(self, widget):
        QMainWindow.__init__(self)

        # Exit QAction
        exit_action = QAction("Exit", self)
        exit_action.setShortcut("Ctrl+Q")
        exit_action.triggered.connect(self.exit_app)

    @Slot()
    def exit_app(self, checked):
        sys.exit()

class CustomTableModel(QAbstractTableModel):
    def __init__(self, data=None):
        QAbstractTableModel.__init__(self)

class Widget(QWidget):
    def __init__(self):
        QWidget.__init__(self)

        # Getting the Model
        self.model = CustomTableModel()

def main():
    app2 = QApplication()
    widget = Widget()
    window2 = MainWindow(widget)
    window2.show()
    sys.exit(app2.exec_())

if __name__ == "__main__":
    app = QApplication()
    widget = Widget()
    window = MainWindow(widget)
    window.show()
    sys.exit(app.exec_())

Answer 1

如 cmets 中所述，Qt 应用程序只能并且应该有一个 QApplication（您可能不遵循此规则，但不能保证它可以正常工作），因此您将不得不重组您的代码。

假设您希望 Q1 窗口位于第一个窗口，当该窗口关闭时，Q2 窗口将打开，这并不意味着您在任何时候都必须使用多个 QApplication。这个想法是要知道窗口何时关闭并收到通知，要知道窗口何时关闭，然后您必须重写窗口的 closeEvent 方法并发出通知，您必须发送一个信号。

综合以上情况，解决办法是：

├── main.py
├── Q1.py
└── Q2.py

ma​​in.py

import sys

from PySide2 import QtWidgets as qtw

import Q1 as record
import Q2 as display


def main():
    app = qtw.QApplication(sys.argv)

    w1 = record.get_mainwindow()
    w2 = display.get_mainwindow()

    w1.closed.connect(w2.show)

    w1.show()

    sys.exit(app.exec_())


if __name__ == "__main__":
    main()

Q1.py

from PySide2 import QtWidgets as qtw
from PySide2 import QtGui as qtg
from PySide2 import QtCore as qtc


class MainWindow(qtw.QMainWindow):
    closed = qtc.Signal()

    def __init__(self):
        super().__init__()

        # Create Window layout with a sound widget
        soundboard = qtw.QWidget()
        soundboard.setLayout(qtw.QGridLayout())
        self.setCentralWidget(soundboard)
        sw = SoundWidget()
        soundboard.layout().addWidget(sw)
        # Window Dimensions
        self.setSizePolicy(qtw.QSizePolicy.Expanding, qtw.QSizePolicy.MinimumExpanding)

        sw.sendorder_button.clicked.connect(self.close)

    def closeEvent(self, event):
        self.closed.emit()
        super().closeEvent(event)


class SendOrderButton(qtw.QPushButton):
    button_stylesheet = "background-color: blue; color: white;"

    def __init__(self):
        super().__init__("Send Order")
        self.setSizePolicy(qtw.QSizePolicy.Expanding, qtw.QSizePolicy.Expanding)
        self.setStyleSheet(self.button_stylesheet)

    def press_button(self):
        if self.isEnabled():
            self.setEnabled(False)
            self.setText("Send Order")
        else:
            self.setEnabled(True)
            self.setText("Sent")


class SoundWidget(qtw.QWidget):
    def __init__(self):
        super().__init__()
        self.setLayout(qtw.QGridLayout())

        # Send Order Button
        self.sendorder_button = SendOrderButton()
        self.sendorder_button.setShortcut(qtg.QKeySequence("Tab"))
        self.layout().addWidget(self.sendorder_button, 5, 0, 1, 2)


def get_mainwindow():
    window = MainWindow()
    return window


if __name__ == "__main__":
    import sys

    app = qtw.QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())

Q2.py

from PySide2 import QtCore as qtc
from PySide2 import QtWidgets as qtw


class MainWindow(qtw.QMainWindow):
    def __init__(self, widget):
        super().__init__()

        file_menu = self.menuBar().addMenu("&File")

        # Exit QAction
        exit_action = qtw.QAction("Exit", self)
        exit_action.setShortcut("Ctrl+Q")
        exit_action.triggered.connect(self.close)

        file_menu.addAction(exit_action)


class CustomTableModel(qtc.QAbstractTableModel):
    pass


class Widget(qtw.QWidget):
    def __init__(self):
        super().__init__()

        # Getting the Model
        self.model = CustomTableModel()


def get_mainwindow():
    widget = Widget()
    window2 = MainWindow(widget)
    return window2


if __name__ == "__main__":
    import sys

    app = qtw.QApplication()
    widget = Widget()
    window = MainWindow(widget)
    window.show()
    sys.exit(app.exec_())